hardcore misery
New Member
on my last reply, i did'nt noticed that the file was not attatched, but i will attatch my schematic, a revised one, after reading your last reply sir...
so to clarify things:
if the max. capacity of the battery (on terms of current) is 950maH,
getting its 3% is equal to 28.5maH. using 4ohms as a limitter,
the voltage across this is 0.114V(28.5maH * 4ohms) and this 0.114V is divided to 2, which is equal to 57mV, and we should made a Vref of at least 57mV also? btw, are these all correct? do i need to divide the 0.114V?
question1: on the previous experiment, for example, the battery voltage to be charge is 3.7V, and the charge voltage is 4.2V, why does when we connect the battery, the voltage sensed by the comparator increases to atleast 3.8 or 3.9V, i know this is due to the charge voltage which is higher than 3.7V, but may i know how to compute for that voltage increase?
question2
n the previous experiment again, when the charger tends to shut-off when the voltage sensed by the comparator reaches 4.2V(but the battery is undercharged)... on the revised circuit from which the voltage to be sense is the voltage drop on the 4ohms, do we expect in nearly fully charged condition of the battery, that if we measure the voltage across the battery in charging condition(yes this is not important, but for curiosity purposes only) the Voltage is already 4.2V?despite of the voltage to be sense by the comparator decreases until the 3% of the icharge is reached?
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we will remove the R3/R4 on the circuit, if the battery voltage is 3.6V, the voltage at the - input is 4.2V - 3.6V = 0.6V; 0.6V/2 = 0.3V
but as the battery approaches in fully charged condition,this 0.3V tends to decrease until the charging current is equal to 3% of the charge capacity, so therefore, we should not depend on the voltage of the battery under charging condition, but we should base the Vref on the 3% of current capacity. are these true?
so if the Voltage drop on the 4 ohms resistor tends to decrease, i think we should put this input on the +feedback of the comparator, and the Vref will be set to the -feedback of the comparator? about the hysterysis, we should not remove this? and put also the hysterysis on the -feedback?
so to clarify things:
if the max. capacity of the battery (on terms of current) is 950maH,
getting its 3% is equal to 28.5maH. using 4ohms as a limitter,
the voltage across this is 0.114V(28.5maH * 4ohms) and this 0.114V is divided to 2, which is equal to 57mV, and we should made a Vref of at least 57mV also? btw, are these all correct? do i need to divide the 0.114V?
question1: on the previous experiment, for example, the battery voltage to be charge is 3.7V, and the charge voltage is 4.2V, why does when we connect the battery, the voltage sensed by the comparator increases to atleast 3.8 or 3.9V, i know this is due to the charge voltage which is higher than 3.7V, but may i know how to compute for that voltage increase?
question2
_________________________
we will remove the R3/R4 on the circuit, if the battery voltage is 3.6V, the voltage at the - input is 4.2V - 3.6V = 0.6V; 0.6V/2 = 0.3V
but as the battery approaches in fully charged condition,this 0.3V tends to decrease until the charging current is equal to 3% of the charge capacity, so therefore, we should not depend on the voltage of the battery under charging condition, but we should base the Vref on the 3% of current capacity. are these true?
so if the Voltage drop on the 4 ohms resistor tends to decrease, i think we should put this input on the +feedback of the comparator, and the Vref will be set to the -feedback of the comparator? about the hysterysis, we should not remove this? and put also the hysterysis on the -feedback?